Pollution-free kitchen ventilator

ABSTRACT

A ventilating hood has an ascending exhaust duct equipped with a series of air cleaning and purifying instrumentalities for removing grease, smoke and fumes generated by cooking equipment. Air rising through the duct passes successively through a grease extractor, an electrostatic precipitator, an activated charcoal filter and a deodorizing chemical spray. The grease extractor and precipitator are provided with hot water and detergent washing sprays. The hood has hollow walls containing air supply conduits for fresh air outlets which discharge streams of fresh air for sweeping into the exhaust duct smokey and grease-laden air from the cooking equipment. A control system provides an automatic wash and dry cycle for the grease extractor and precipitator and includes thermostatic control means for closing fire dampers and turning on the water sprays in case of fire in the ventilator.

Gaylord atent I191 Jan. 15, 1974 [73] Assignee: Gaylord Industries, Lake Oswego,

Oreg.

[22] Filed: Aug. 2, 1971 [21] Appl. No.1 168,019

55/316, 55/DIG. 36, 98/115 K [51] Int. Cl B0ld 50/00 [58] Field of Search 55/124, 118, 242, 55/126, 120, 139, 122, 217, 220, 316, 279,

DIG. 36; 98/115 K OTHER PUBLICATIONS Super Compact Line Electronic Air Cleaner Models 908 to 932 Manual SC900 C Emerson Electric dtd 11/24/69 pages l-1O Primary Examiner-Bernard Nozick Att0rneyL ee R. Schermerhorn [57] ABSTRACT A ventilating hood has an ascending exhaust duct equipped with a series of air cleaning and purifying instrumentalities for removing grease, smoke and fumes generated by cooking equipment. Air rising through the duct passes successively through a grease extractor, an electrostatic precipitator, an activated charcoal filter and a deodorizing chemical spray. The grease extractor and precipitator are provided with hot water and detergent washing sprays. The hood has hollow walls containing air supply conduits for fresh air outlets which discharge streams of fresh air for sweeping into the exhaust duct smokey and grease-laden air from the cooking equipment. A control system provides an automatic wash and dry cycle for the grease extractor and precipitator and includes thermostatic control means for closing fire dampers and turning on the water sprays in case of fire in the ventilator.

15 Claims, 12 Drawing Figures PATENTEDJAR 15 m 3,7 l 2 SHEET 10F 6 INVENTOR Aso K. Gaylord ATTORNEY PATENTEBJAM 15 m4 37 51 sum-312m 6 WI H i122 INVENTOR 1:79 2 Aso K. Gaylord BY 6J ATTORNEY PNENTEU JAN 1 5 IBM SHEET 30F 6 INVENTOR Asa K. Gaylord ATTORNEY PATENTEDJAN 15 m4 3. 785; l 24 SHEET u BF 6 INVENTOR Asa K. Gaylord PVENFED me 15 I974 SHEET 5 CF 6 INVENTOR Asa K. Gaylord ATTORNEY PATENTEUJAW 15 1974 SHEET E OF 6 ZOO INVENTOR Asa K. Gaylord ATTOREY POLLUTION-FREE KITCHEN VENTILATOR BACKGROUND OF THE INVENTION This invention relates to a pollution-free kitchen ventilator, particularly for restaurant use.

The ventilators of restaurant kitchens discharge large amounts of smokey, grease-laden and malodorous air which is often objectionable in the neighborhood. Previous kitchen ventilators have been designed primarily to remove grease droplets which create a fire hazard in the ventilator itself but have done little or nothing toward preventing smoke and objectionable odors from discharging into the atmosphere. Existing ventilators have succeeded in providing fresh air for the workers in the kitchen and the very effectiveness of these ventilating systems has caused even more contamination of the outside air adjacent the restaurant.

Objects of the invention are, therefore, to provide a pollution-free kitchen ventilator, to provide a ventilator which removes smoke, fumes and cooking odors as well as grease from the air discharged from the kitchen, to provide a kitchen ventilator having an electrostatic precipitator for removing smoke and having an activated charcoal filter and deodorizing chemical spray means for removing cooking odors, to provide a ventilating hood having improved fresh air makeup means arranged to sweep contaminated air into the exhaust duct, to provide a control system having an automatic wash and dry cycle for a grease extractor and electrostatic precipitator, and to provide a ventilator of the type described having an improved fire control system arranged to close fire dampers and activate fire extinguishing and quenching devices.

SUMMARY OF THE INVENTION In the present construction a hood overhangs the cooking equipment in a position to intercept smoke, fumes and grease-laden air generated by the cooking operations. The hood has hollow walls containing fresh air supply ducts for a number of air outlet openings.

These openings direct streams of fresh air toward the inlet opening of an exhaust duct, sweeping the smokey and grease-laden air into the exhaust duct. The air in the exhaust duct passes first through a grease extractor to remove grease droplets, then through an electrostatic precipitator to remove smoke, then through an activated charcoal filter to remove most of the objectionable odors and, finally, through a deodorizing chemical spray which removes any residual odors.

The grease extractor and precipitator are provided with hot water and detergent washing spray means. A control system provides a wash and dry cycle. During the wash period the ventilating fan is turned off and the water sprays are turned on, cleaning the grease extractor and precipitator. Then during the drying period of the cycle the water is turned off and the fan is turned on to draw a current of air through the grease extractor and precipitator. In case of fire, the water sprays are automatically turned on and fire dampers are closed in both the exhaust and air supply ducts.

The invention will be better understood and additional objects and advantages will become apparent from the following description of the preferred embodiment illustrated in the accompanying drawings. Various changes may be made, however, in the details of construction and arrangement of parts and certain features may be used without others. All such modifications within the scope of the appended claims are included in the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view, with parts broken away, showing a ventilator embodying the invention;

FIG. 2 is a view on the line 22 in FIG. 1;

FIG. 3 is an end elevation view of the right end of the ventilator in FIG. 1;

FIG. 4 is a fragmentary elevation view of an upper portion of the fresh air supply duct;

FIG. 5 is a similar view of an upper portion of the exhaust duct;

FIG. 6 is an elevation view of the left end of the ventilator in FIG. 1 including the plumbing connections;

FIG. 7 is a perspective view of the control unit for the electrostatic precipitator;

FIG. 8 is a fragmentary sectional view on the line 88 in FIG. 7;

FIG. 9 is an elevation view of the exhaust damper control unit with parts broken away;

FIG. 10 is an exploded perspective view of the con trol unit for the fresh air damper in FIG. 4;

FIG. 11 is a wiring diagram for the damper motor in FIG. 10; and

FIG. 12 is a wiring diagram of the control system.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIGS. 1 and 2, the numeral 9 designates cooking equipment, such as a range, which generates smoke, fumes and grease-laden air to be removed from the kitchen. This air is captured by an open front hood 10 having a hollow back wall 11, hollow end walls 12 and 13 and a hollow top wall 14. The hood may also be used with broilers, soup kettles, deep fat fryers, etc.

As best shown in FIG. 1, each end wall 12 and 13 comprises spaced apart inner and outer vertical sheets of metal 15 and 16 defining an air inlet duct chamber 20 therebetween. As seen in FIG. 2, back wall 11 comprises inner and outer, vertically extending sheets of metal 21 and 22 defining an air inlet duct chamber 23 therebetween. In a similar manner, top wall 14 comprises inner and outer, horizontally extending, sheets of metal 24 and 25 defining an air inlet duct chamber 26 therebetween.

Each end chamber 20 extends upward through a vertical duct section 30 which is adapted to connect at its upper end with a fresh air supply duct 31 containing an air supply fan 32 as shown in FIG. 4. Although both left and right ducts 30 may be supplied with fresh air, the present system is arranged to operate satisfactorily with fresh air supplied to only one of the ducts 30, the top of the other then being closed by a cap 29 as shown in FIG. 1. This provides the option of using the duct 30 which is most convenient for connection with the exterior supply duct. The fresh air supply duct 31 is opened and closed by the damper 33 in FIG. 4.

Each duct 30 contains a flow balancing damper 35 and a fire damper 36. Dampers 35 are adjusted when the unit is installed and thereafter remain in fixed position. Fire dampers 36 are pivotally mounted to close the ducts 30 in case of fire. Each damper 36 is connected by a link 37 with an arm 38 on a main fire damper shaft which will presently be described in detail. Removable front panels 39 provide access to these dampers and the operating linkage.

Incoming fresh air follows the paths of arrows 41 in FIG. 1. In the lower part of chamber the air flow divides, portions passing through hollow back wall chamber 23 and hollow top wall chamber 26 to a chamber corresponding to chamber 20 in the right side end wall 13.

The inside surfaces of end walls 12 and 13 adjacent their front ends are provided with vertically extending fresh air discharge slots 45. The air issuing from these slots is directed rearwardly and the flows at the opposite ends of the hood are balanced by pivotally mounted balancing baffles 46. Baffles 46 perform the dual function of deflecting the air from slots 45 in a rearward direction and also acting as dampers to equalize the flows from the left and right ends of the hood. These baffles are manually adjusted at the time of installation and remain in fixed position thereafter.

Similarly, the under side of hollow top wall 14 is provided with a fresh air discharge slot 47 extending along the front edge ofthe top wall. This slot is equipped with a pivotally mounted balancing baffle 48 which directs the air flow rearwardly and also serves as a damper to obtain the proper balance olair flows through the three discharge openings 45, 45 and 47.

The upper edge of the metal sheet 21 which forms the front side of hollow rack wall 11 terminates a short distance below the under side of top wall 14 to form an exhaust air inlet throat opening 50 extending the length of the hood between its end walls 12 and 13. The fresh air 41 discharged from outlet slots 45, 45 and 47 is directed rearwardly toward throat 50 so as to sweep along with it room air from the kitchen designated by arrows 51 in FIG. 2. All of these air currents pass rearwardly over the cooling equipment 9, sweeping fumes, smoke, odors and grease-laden air from the cooking equipment into exhaust throat 50. This combined exhaust flow coming from the various sources mentioned is designated by arrows 52.

From inlet throat 50 the exhaust flow 52 passes upward successively through an exhaust duct having a grease extractor section 55, electrical precipitator section 56, an activated charcoal filter 57 and a chemical deodorizing spray 58. At the top of the column a collar 60 connects with an exhaust outlet duct 61 containing an exhaust fan 62 as shown in FIG. 5.

Exhaust fan 62 has a greater flow capacity than fresh air supply fan 32 in order to remove some air 51 from the kitchen in additon to the total inlet flow 41. This relationship of the capacities of the exhaust and supply fans draws into the exhaust duct a flow of kitchen air 51 whcih not only ventilates the kitchen but also assists in sweeping the cooking odors, fumes and smoke back into the exhaust throat opening 50 from the front parts of the cooking equipment.

Grease extractor comprises a series of baffles projecting from opposite sides of the exhaust passageway to create a tortuous flow path for the air and cause grease particles to impinge against the baffle surfaces and be separated from the air stream by centrifugal force. The lower end of the exhaust duct terminates at a grease trough or gutter 65 just below and inside of the inlet throat 50. Trough 65 spans the distance between inner and outer metal sheets 21 and 22 and forms a top wall in the back inlet chamber 23. The grease trough is equipped with a drain pipe 66.

The upper side of inlet throat 50 is defined by a downward sloping damper baffle 67 which is pivotally mounted on shaft 40 which was previously mentioned with reference to FIG. 1. When this baffle is in its open operative position shown in FIG. 2, it functions as a first grease extracting baffle, causing the entering flow of grease-laden air to turn abruptly around its lower edge. In case of fire, the baffle rotates clockwise with shaft 40 to form a damper closing the exhaust passageway just inside the inlet throat 50.

Damper baffle 67 closes against a stationary baffle 68 on the metal sheet 22. Above baffle 68 is a troughshaped baffle 69 on a door panel 70 hinged at 106 on the front side of the exhaust duct. Trough 69 drains into gutter 65. These grease extracting baffles and duct surfaces are sprayed for cleaning and fire extinguishing purposes by spray nozzles 71 connected with a hot water and detergent supply pipe 72. A tube 73 connected with the pipe 72 discharges a stream of hot water and detergent directly into drain pipe 66 when the sprays are operating, to keep the drain pipe 66 free of congealed grease.

Electrostatic precipitator 56 comprises a series of cells extending horizontally side by side the length of the hood between the vertical end ducts 30. The cells have spaced apart vertical plates between which the smoke-laden air passes in rising through the exhaust duct. An electrostatic field between the plates causes smoke in the exhaust flow to separate from the air stream and deposit on the plates whereby smoke-free air is discharged from the exhaust duct, Hence, the plates in the precipitating cells must be cleaned from time to time to remove the smokey deposits that accumulate thereon. The present arrangement provides for cleaning the plates without removing the cells from the exhaust duct.

The precipitator is cleaned by a series of upwardlydirected, lower washing sprays 75 and a series of downwardly-directed, upper washing sprays 76 used alternately. The hot water and detergent from these sprays drains down through the grease extractor 55, providing an additional wash for the surfaces in the extractor and passes into trough 65 for disposal through drain pipe 66. Lower sprays 75 are generated by spray nozzles 77 in a lower supply pipe 78 and upper sprays 76 are generated by spray nozzles 79 in an upper supply pipe 80.

After the grease and smoke have been removed as just described, remaining fumes and odors are largely removed by the activated charcoal filter 57 above the upper spray pipe 80. Any remaining odors are neutralized by chemical deodorizing sprays 58 generated by upwardly directed spray nozzles 81 in a supply pipe 82. The active ingredient in sprays 58 may be any one of a number of substances commonly used in room freshener deodorants. With the grease, smoke and fumes thus removed and the cooking odors removed, neutralized or masked, the exhaust air is clean enough to be discharged back into the kitchen, if desired, but ordinarily it is discharged out-of-doors in order to remove spray pump CPl from a chemical tank 89 containing a float switch SW5.

As shown in FIGS. 1 and 2, the electrostatic precipitator cells are contained in four removable units 100, each having a plurality of spaced apart vertical precipitating plates 101. Each unit is equipped with a handle 102 so that the unit may be pulled out on a supporting rack. These units are energized by removable plugs PLI, PL2 connected to high voltage circuit wires 103. Pairs of the units 100 are accessible behind two doors 105, each pivoted at the bottom on a hinge 106 and equipped with a latch handle 107. In FIG. 1 the left door is open and the right door 105 is closed. When doors 105 are closed, each door engages and depresses a pair of plungers 108 and 109 in a safety control box 110.

As shown in FIGS. 7 and 8, the closing of door 105 depresses plunger 108 to close a switch SW7 in the power supply for the precipi-tating units. As a further safety precaution, plunger 109 normally holds open a safety grounding switch SW9 in the high voltage circuit which energizes the circuit wires 103. When either one of doors 105 is opened, the opening of its switch SW7 disconnects the power supply from the precipitator and spring 111 closes the grounding switch SW9.

Charcoal filters 57 are insertable and removable through doors 112 in FIGS. 1 and 2.

A snuffer fire extinguishing system is shown in FIGS. 1 and 3. In case of fire under the hood, a carbon dioxide pressure tank 115 is arranged to discharge fire extinguishing gas through pipe 116 connected with gas nozzles 117. The snuffer system is actuated by a fusible link 120 carried by a holder 121 mounted on the under side of the hollow top wall 14 of the hood as shown in FIG. 2. Fusing of link 120 releases a tension cable 122 which passes around a pulley 123 and is connected with a cylinder valve 124 in the gas line 116. Valve 124 is spring-tensioned to open position and is normally held closed by cable 122 and fusible link 120.

The details of damper control unit in FIGS. 1 and 2 are illustrated in FIG. 9. As previously described, damper 67 is mounted for rotation on a horizontal shaft 40. The damper is opened and closed by a damper arm 131 connected with an L-shaped bracket 132 on the front of the damper whereby arm 131 has pivotal movement on the axis of shaft 40. Arm 131 is an angle iron of L-shape in cross section having an upper end extending into the control unit 130.

A flange 133 on the back side of arm 131 is equipped with a leaf spring 134. A slidable control rod 135 has a pin 136 engageable with the front side of flange 133 and a pin 137 engageable with the back side of spring 134. The front end of rod 135 projects through the front wall of unit 130 inside of a sleeve 138 which is slidable on the rod. The outer end of sleeve 138 is equipped with a handle 140 having a stop 141 within the sleeve to engage the end of rod 135. The inner end of sleeve 138 is equipped with a circular latch release plate 142.

A vertical catch plate 145 is secured to rod 135 by bolt 146. A roller 147 on the lower end of catch plate 145 rolls on the bottom wall of the housing 148. A compression spring 150 on rod 135 has an outer end abutting catch plate 145 and an inner end abutting a wall 151 in housing 148. Fan switch SW3 is mounted on housing 148 in the path of movement of catch plate 145.

A latch or trigger arm 155 extends horizontally above the rod 135, its back end being pivotally mounted on a pin 156 in a bracket 157 on the wall 151. The front end of trigger arm 155 is connected with a link 158 on an armature 160 in a vertical solenoid coil CL2. The under side of arm 155 is provided with a cam surface 161 which is engageable by release plate 142 and a notch 162 engageable with the upper end of catch plate 145.

The parts are shown in normal operating condition with the damper 67 open as in FIG. 2. Catch plate 145 engages switch SW3 to hold it closed and maintain operation of the fans 32 and 62 in FIGS. 4 and 5. Solenoid CL2 is deenergized, allowing its armature 160 to remain in lower position with the upper end of catch plate 145 engaged in notch 162 of trigger arm 155. Catch plate 145 holds spring 150 compressed with rod 135 at the leftward limit of its movement.

The damper may be closed through energization of solenoid CL2 by the control system presently to be described or manually by pulling handle 140 outward. Energization of solenoid CL2 raises its armature 160 and trigger arm 155 to release the catch plate 145. Coil spring 150 then moves rod 135 and sleeve 138 to the right, swinging damper 67 clockwise to closed position against baffle 68. As rod 135 moves to the right, catch plate 145 leaves the switch SW3, causing it to open by an internal spring and shut off the fans 32 and 62.

The same result is obtained by pulling outward on handle 140. Outward movement of sleeve 138 on the rod 135 causes plate 142 to engage cam surface 161 and raise the trigger arm 155 to release catch plate 145.

The damper is reopened by pushing in on handle 140. As handle 140 is pushed inward, stop 141 pushes rod 135 to the left, swinging the damper counterclockwise. Plate 142 slides on cam surface 163, lifting trigger arm 155 and allowing plate 142 to pass behind cam surface 161 while catch plate 145 engages cam surface 164 and enters notch 162 allowing trigger arm 155 to fall back to latched position as shown. This brings latch plate 145 back into engagement with switch SW3 to re-start the fans 32 and 62.

The damper control unit for fresh air supply damper 33 in FIG. 4 is illustrated in FIGS. 10 and 11. The shaft of motor DMl extends through spring housing 171 and is connected with damper shaft 172 by coupling 174. When the ventilating system is not operating, damper 33 is held closed in vertical position against stops 173, as shown, by spring 175. Energization of motor DMl rotates the shafts 170 and 172 counterclockwise to open the damper to horizontal positon,

tightening the spring 175.

Cam 176 is adjusted to open motor switch 177 after 90 rotation when the damper is in horizontal, wide open position, and apply a brake to hold the damper open. As long as motor switch 177 is closed, there is insufficient current flow through brake solenoid 178 to make the brake effective. When switch 177 opens, there is then sufficient current flow through brake solenoid 178 to hold the damper open against the tension of return spring 175. This is the normal position of the parts while the ventilating system is operating.

Deenergization of the circuit at terminals 180, 181 releases the brake and allows spring to return the damper and motor in clockwise rotation to closed position as shown in FIG. 10. As this occurs, cam 176 recloses switch 177 in preparation for the next operation of the motor.

Control System The control system is illustrated in FIG. 12. The system is energized from a pair of supply wires 200, 201. A timing motor TMl is energized by the closing of relay contacts C1 in response to the energization of relay coil CL4. The timing motor is a conventional device which is started by the momentary closure of contacts C1 to rotate a one revolution cam shaft 202. When cam shaft 202 starts to rotate, a self-contained switch, not shown, holds the timing motor energized for one revolution and then stops the timing motor in condition for re-starting by relay contacts C1 in a new cycle of operation.

A fire alarm relay CLI and damper control coil CL2 are connected in parallel between line 200 and a wire 203. Wire 203 may be energized from line 201 either by a manual remote fire switch SW1 or a thermostatic switch THl which appears in the exhaust duct in FIG. 2. Wire 203 also energizes a time delay relay CL3 which is arranged to close a pair of switches C2 and C3 for an interval and then open them. Switch C2 energizes a wire 204 and switch C3 energizes a wire 205.

Timing motor cam shaft 202 actuates a plurality of switch arms C4, C5, C6, C7, C8 and C9. These switch arms are engageable with the contacts 211-221. Switch arm C4 is connected with line 201. Contact 212, switch arm C5 and switch arm C6 are connected together by a wire 222. Contact 216 and switch arm C7 are connected together by a wire 223. Contacts 218 and 219 are connected to a wire 224. Switch arm C8 is connected to a' wire 225. Contact 221 is connected to a wire 226. Contact 213 is connected to a wire 227, contact 215 is connected to a wire 228, contact 217 is connected to wire 204 and contact 211 is connected to wire 205.

A pushbutton stop switch SW2 has a normally open switch arm SW2-1 and a normally closed switch arm SW2-2. The former connects timer relay coil CL4 with wire 224 through a fuse 229 and the latter connects timer switch arm C9 with wire 224.

A pushbutton start switch SW6 connects wire 226 with a wire 230 to energize starter coil CLS for the exhaust fan 62, starter coil CL6 for fresh air supply fan 32, damper motor DM1 and chemical spray pump CPl. In series across switch SW6 are damper switch SW3, water pressure switch SW4, chemical tank float switch SW5 and exhaust fan starter contact C10 which is closed by starter coil CL5.

Water solenoid valve SV3 and detergent pump DP3 are energized by wire 204. Water solenoid valve SV2 is energized by wire 228 and detergent pump DP2 is energized by wire 227. Water solenoid valve SV1 and detergent pump DPl are energized by wire 205.

A wire 235 connected to timer contact 220 energizes precipitator power pack 236 through plug PLl, door switches SW7, toggle switch SW8 and plug P152, all in series.

Snuffer tank pressure switch SW10 connects wire 230 with wire 240 to energize electric cooking equipment relay CL7. A solenoid gas valve SV4 controls the cooking equipment operated by gas burners. This valve is normally energized by contacts C12 in a gas shutoff relay 241. Relay coil CL8 holds contacts C11 and C12 closed. Contacts C11 are shunted by reset pushbutton switch SW12.

Start-Up The system is put into operation by pushing in handle 140 to open exhaust damper 67 to its FIG. 9 position and then momentarily closing pushbutton start switch SW6 in FIG. 12. This energizes wire 230 through wire 226, contact 221, timer switch arm C9, normally closed stop switch arm SW2-2, fuse 229, wire 224, contact 218, timer switch arm C7, wire 223, contact 216, timer switch arm C6, wire 222, contact 212 and timer switch arm C4 which is connected to supply line 201. The energization of wire 230 energizes starter coil CLS for the relay controlling exhaust fan 62, starter coil CL6 for the relay controlling fresh air supply fan 32, damper motor DMl which opens the damper 33 in air supply duct 31 and chemical spray pump CPl.

The momentary energization of exhaust fan starter coil CL5 closes contacts C10 in the exhaust fan relay to establish a holding circuit through the normally closed switches SW3, SW4 and SW5 in series to maintain the energization of wire 230 after pushbutton start switch SW6 has re-opened.

Wire 230 also energizes the power pack 236 of electrostatic air cleaner 56 through wire 225, timer switch arm C8, contact 220, wire 235, plug PLI, door switches SW7, toggle switch SW8 and plug P152. Power pack 236 supplies high voltage power to the plates 101 in electrostatic cleaner cells 100. Safety grounding switches SW9 are normally open.

Wash Cycle The wash cycle is initiated by the momentary pushing of pushbutton stop switch SW2. This causes switch arm SW2-2 to break the holding circuit just described for exhaust fan relay CL5 which then opens its relay contacts C10. This deenergizes wire 230 thereby also deenergizing air supply fan relay CL6, the brake in damper motor DMl, chemical spray pump CPI and wire 225 thereby de-activating the electrostatic air cleaner by deenergization of power pack 236. These operations stop the ventilating functions.

The momentary pushing of stop switch SW2 also closes the normally open switch arm SW2-1 to energize timer relay coil CL4. The energization of relay coil CL4 closes timer motor contacts C1 to start timing motor TMl. The operation of the timing motor maintains the energization of its circuit for one revolution of cam shaft 202. After a short interval, timer contact arm C4 shifts from contact 212 to contact 211, energizing wire 205 from supply line 201. Wire 205 energizes detergent pump DPl and solenoid valve SVl to open this valve and activate washing spray to wash the precipitator cells from below.

After a predetermined period of time, timer switch arm C4 leaves contact 211 and returns to contact 212 which turns off the lower wash sprays 75. At this time, timer switch arm C5 shifts to contact 213 and switch arm C6 shifts to contact 215 to energize wires 227 and 228 from supply line 201. These switch operations energize detergent pump DP2 and solenoid valve SV2 to supply hot water and detergent for upper wash sprays 76 to wash the precipitator cells from above.

After another predetermined period of time, timer switch arm C5 returns to contact 214, deenergizing detergent pump DP2. Timer switch arm C6 remains on contact 215 to hold open solenoid valve SV2 for a further period of time to provide a hot water rinse of the precipitator cells from above. Exhaust damper 67 remains open during the wash and rinse operations to pass the water into trough 65 and drain pipe 66.

At the end of the rinse period, timer switch arm C6 returns to contact 216, deenergizing wire 228 and shutting off the hot water rinse. At this time, timer switch arm C7 shifts to contact 217 energizing wire 204 to start detergent pump DP3 and open solenoid valve SV3 to supply hot water and detergent through spray nozzles 71 and tube 73 in the grease extractor section 55.

After this wash period, timer switch arm C7 returns to contact 218, shutting off the wash sprays in grease extractor section 55 and, at the same time, timer switch arm C8 shifts to contact 219 to energize wires 225 and 230 thereby energizing the starter coils CLS and CL6 in the exhaust fan and fresh air supply fan relays. This circuit is maintained for a predetermined period to pass air through the exhaust duct for drying the precipitator cells. It will be noted that this circuit does not energize power pack 236 whereby the precipitator cells remain deenergized and inactive. Fresh air damper motor DMl is energized to open damper 33 and chemical pump CPI is energized. At the beginning of the drying period timer switch arm C9 leaves contact 221 to break the redundant circuit from wire 224 through stop switch arm SW2-2 to relay contacts C10.

After a drying period, timer switch arm C8 returns to contact 220, stopping the fans and terminating the drying period and opening relay contacts C10. Timer switch arm C9 returns to contact 221. All the timer switch arms C4, C5, C6, C7, C8 and C9 have now returned to their normal positions shown in FIG. 12 and, after a brief further interval completing one revolution of cam' shaft 202, timing motor TMl mechanically opens contactsCI in its own energizing circuit to stop the timing motor. The ventilator is then ready to resume operation by momentarily closing start switch SW6.

Fire Control Operation Upon closing of thermostat THl or remote manual fire switch SW1, damper control solenoid CL2 is energized to close the exhaust duct fire damper 67. This mechanical action opens damper switch SW3 to deenergize wire 230 and fan relay coils CL and CL6 to stop the exhaust and fresh air supply fans. Deenergization of wire 230 also deenergizes power pack 236, deactivating the precipitator.

Simultaneously, time delay relay coil CL3 is energized, closing switches C2 and C3 to energize wires 204 and 205. The energization of these wires opens solenoid valves SV3 and SVI and operates detergent pumps DP3 and DPl to operate water sprays from the nozzles 77 and 71 for fire protection. The weight of any accumulation of water on the closed damper 67 will slightly compress the extended spring 150 in FIG. 9 and force the damper open sufficiently to allow the water to escape to trough 65.

Upon deenergization of relay CL3 by the re-opening of thermostatic switch TI-ll or manual switch SW1, switches C2 and C3 remain closed to maintain the water sprays for a preset delay period. At the end of the preset period, switches C2 and C3 open, closing solenoid valves SV3 and SVl and stopping detergent pumps DP3 and DP].

Closing switches THl or SW1 also energizes fire alarm relay coil CLl to actuate a fire alarm system.

The cooling equipment is also shut off by the closing of switches THl and SW1. Relay coil CL7 controls the supply of electrical service to electric cooking equipment and solenoid valve SV4 controls the supply of gas fuel to gas cooking equipment. Both CL7 and SV4 are normally energized by wire 230 to maintain cooking operations when the fresh air supply and exhaust fans 32 and 62 are running and are deenergized whenever these fans are stopped, to shut off the cooking equipment.

In the event of a substantial decrease in pressure in snuffer tank 115 in FIG. 3, pressure switch SW10 opens and deenergizes CL7, CL8 and SV4, thereby shutting off the supply of electrical service and gas fuel to the cooking equipment. The snuffer tank must be recharged and pressurized to re-close switch SW10 and enable CL7, CL8 and SV4 to be re-energized. Upon restarting the fans 32 and 62 by closing start switch SW6, the electrical and gas service to the cooking equipment is reestablished by momentary closing of reset switch SW12 to energize relay coil CL8, closing contacts C11 and C12 and re-opening solenoid valve SV4.

Opening of either pressure switch SW4 by low water pressure or float switch SW5 by low chemcial spray supply breaks the circuit to CLS to stop the fans 32 and 62 and de-activate the precipitator.

Opening of any access door to the precipitator compartment deenergizes the precipitator power pack 236 by opening of the door switch SW7. Simultaneously, the precipitator cells and entire high voltage system are grounded for safety by switch SW9 in FIG. 8. Removal of the cover from the power pack assembly 236 de-activates the precipitator system and isolates it from line voltage by breaking the circuit through plugs PL1 and PL2. The precipitator may also be de' activated by opening toggle switch SW8.

Chemical spray pump CPI and damper opening motor DMl are activated whenever the fans 32 and 62 are running, these devices being wired in parallel with CLS and CL6.

Having now described my invention and in what manner the same may be used, what I claim as new and desire to protect by Letters Patent is:

l. Ventilating apparatus for kitchen cooking equipment comprising a hood adapted for mounting above said cooking equipment, said hood having a hollow back wall, a pair of hollow end walls and a hollow top wall, an exhaust duct in an upper portion of said back wall having an inlet opening under said top wall for smoke and grease-laden air from said cooking equipment, a grease extractor in said exhaust duct in said hollow back wall, an upper air outlet opening extending along the under side of said top wall at the front edge thereof, a pair of end air out-let openings extending along front edge portions of said end walls, an air supply duct in said top wall for said upper outlet opening, and air supply ducts in said end walls for said end outlet openings, said ducts in said end walls being connected with said duct in said top wall.

2. Apparatus as defined in claim 1 including an electrostatic precipitator in said exhaust duct downstream from said grease extractor.

3. Apparatus as defined in claim 2 including an activated charcoal filter in said exhaust duct downstream from said precipitator.

4. Apparatus as defined in claim 3 including deodor izing chemical spray means in said exhaust duct downstream from said charcoal filter.

5. Apparatus as defined in claim 4 including washing spray means for said grease extractor and precipitator.

6. Apparatus as defined in claim 5, said exhaust duct extending upward from said inlet opening with said grease extractor, precipitator, charcoal filter and deodorizing spray being disposed one above the other so that wash liquid from said precipitator drains through said grease extractor, and said charcoal filter and deodorizing spray are above said washing sprays.

7. Ventilating apparatus for kitchen cooking equipment comprising a hood adapted for mounting above said cooking equipment, an ascending exhaust duct having an inlet opening in said hood for smoke and grease-laden air from said cooking equipment, a grease and liquid collecting trough having a drain in the lower end of said duct, a grease extractor in said duct above said inlet opening, an electrostatic precipitator in said duct above said grease extractor, washing spray nozzles in said duct arranged to wash said grease extractor, washing spray nozzles in said duct directed upward toward the under side of said precipitator, and washing spray nozzles in said duct directed downward toward the upper side of said precipitator, the washing liquid from said precipitator draining through said grease extractor to said trough.

8. Apparatus as defined in claim 7 including a charcoal filter in said duct above said precipitator, and a deodorizing chemical spray in said duct above said filter.

9. Ventilating apparatus for kitchen cooking equipment comprising a hood adapted for mounting above said cooking equipment, an exhaust duct in said hood having an inlet opening for smoke and grease-laden air from said cooking equipment, an air supply duct in said hood having an outlet opening in spaced relation to said inlet opening, a grease extractor in said exhaust duct, an electrostatic precipitator in said exhaust duct downstream from said grease extractor, an activated charcoal filter in said exhaust duct downstream from said precipitator, deodorizing chemical spray means in said exhaust duct downstream from said charcoal filter, and washing spray means for said grease extractor and precipitator.

10. Apparatus as defined in claim 9 including a control system having a start switch arranged to start fans in said exhaust and air supply ducts, energize said precipitator and start said chemical spray means; a timing device; a stop switch arranged to stop said fans and said chemical spray means, deenergize said precipitator and start said timing device; said timing device then starting said washing spray means for a washing period, stopping said washing spray means after said washing period and starting said fans for a drying period, and then stopping said fans.

11. Apparatus as defined in claim 10 including a thermostatic switch in said exhaust duct and fire dampers in said exhaust and air supply ducts, and means in said system actuated by said thermostatic switch in case of fire in said exhaust duct to stop said fans, close said dampers, and operate said washing sprays for fire extinguishing purposes.

12. Ventilating apparatus for kitchen cooking equipment comprising an exhaust duct for smoke and greaseladen air from said cooking equipment; an exhaust fan; a grease extractor and electrostatic precipitator in said duct; washing spray means for said grease extractor and precipitator; a control system; a start switch in said control system arranged to start said fan and energize said precipitator; a timing device in said system; and a stop switch arranged to stop said fan, deenergize said precipitator and start said timing device; said timing device then starting said washing spray means for a washing period, stopping said washing spray means after said washing period and starting said fan for a drying period, and then stopping said fan.

13. Apparatus as defined in claim 12 including a thermostatic switch and fire damper in said duct, and means in said system actuated by said thermostatic switch in case of fire in the duct to stop said fan, close said damper and operate said washing sprays for fire extinguishing purposes.

14. Ventilating apparatus for kitchen cooking equipment comprising a hood adapted for mounting above said cooking equipment, an ascending exhaust duct having an inlet opening in said hood for smoke and grease-laden air from said cooking equipment, a grease and liquid collecting trough in the lower end of said duct and having a drain, a grease extractor in said duct above said inlet opening and trough, washing spray means in said grease extractor arranged to wash said grease extractor, an electrostatic precipitator in said duct above said grease extractor, washing spray means in said duct adjacent said precipitator arranged to wash said precipitator, and means including said duct for draining the washing liquid from said precipitator through said grease extractor into said trough to wash said grease extractor.

15. Ventilating apparatus for kitchen cooking equipment comprising an exhaust duct for smoke and greaseladen air from said cooking equipment, a grease extractor in said duct, said duct extending upward from said grease extractor, an electrostatic precipitator in said duct above said grease extractor, washing spray means in said grease extractor, washing spray means for said precipitator, a control system having a timing device for programming said washing spray means in a wash cycle, said timing device initiating said wash cycle by starting said washing spray means for said precipitator, wash liquid from said precipitator draining through said duct and grease extractor for a first washing of said grease extractor, and said timing device thereafter stopping said washing spray means for said precipitator and starting said washing spray means in said grease extractor for a second washing of said grease extractor, and further including an exhaust fan in said duct, a start switch arranged to start said fan and energize said precipitator, a stop switch arranged to stop said fan, deenergize said precipitator and start said timing device, and means controlled by said timing device to stop said washing spray means in said grease extractor, start said fan for a drying period, and then stop said fan and timing device. 

1. Ventilating apparatus for kitchen cooking equipment comprising a hood adapted for mounting above said cooking equipment, said hood having a hollow back wall, a pair of hollow end walls and a hollow top wall, an exhaust duct in an upper portion of said back wall having an inlet opening under said top wall for smoke and grease-laden air from said cooking equipment, a grease extractor in said exhaust duct in said hollow back wall, an upper air outlet opening extending along the under side of said top wall at the front edge thereof, a pair of end air outlet openings extending along front edge portions of said end walls, an air supply duct in said top wall for said upper outlet opening, and air supply ducts in said end walls for said end outlet openings, said ducts in said end walls being connected with said duct in said top wall.
 2. Apparatus as defined in claim 1 including an electrostatic precipitator in said exhaust duct downstream from said grease extractor.
 3. Apparatus as defined in claim 2 including an activated charcoal filter in said exhaust duct downstream from said precipitator.
 4. Apparatus as defined in claim 3 including deodorizing chemical spray means in said exhaust duct downstream from said charcoal filter.
 5. Apparatus as defined in claim 4 including washing spray means for said grease extractor and precipitator.
 6. Apparatus as defined in claim 5, said exhaust duct extending upward from said inlet opening with said grease extractor, precipitator, charcoal filter and deodorizing spray being disposed one above the other so that wash liquid from said precipitator drains through said grease extractor, and said charcoal filter and deodorizing spray are above said washing sprays.
 7. Ventilating apparatus for kitchen cooking equipment comprising a hood adapted for mounting above said cooking equipment, an ascending exhaust duct having an inlet opening in said hood for smoke and grease-laden air from said cooking equipment, a grease and liquid collecting trough having a drain in the lower end of said duct, a grease extractor in said duct above said inlet opening, an electrostatic precipitator in said duct above said grease extractor, washing spray nozzles in said duct arranged to wash said grease extractor, washing spray nozzles in said duct directed upward toward the under side of said precipitator, and washing spray nozzles in said duct directed downward toward the upper side of said precipitator, the washing liquid from said precipitator draining through said grease extractor to said trough.
 8. Apparatus as defined in claim 7 including a charcoal filter in said duct above said precipitator, and a deodorizing chemical spray in said duct above said filter.
 9. Ventilating apparatus for kitchen cooking equipment comprising a hood adapted for mounting above said cooking equipment, an exhaust duct in said hood having an inlet opening for smoke and grease-laden air from said cooking equipment, an air supply duct in said hood having an outlet opening in spaced relation to said inlet opening, a grease extractor in said exhaust duct, an electrostatic precipitator in said exhaust duct downstream from said grease extractor, an activated charcoal filter in said exhaust duct downstream from said precipitator, deodorizing chemical spray means in said exhaust duct downstream from said charcoal filter, and washing spray means for said grease extractor and precipitator.
 10. Apparatus as defined in claim 9 including a control system having a start switch arranged to start fans in said exhaust and air supply ducts, energize said precipitator and start said chemical spray means; a timing device; a stop switch arranged to stop said fans and said chemical spray means, deenergize said precipitator and start said timing device; said timing device then starting said washing spray means for a washing period, stopping said washing spray means after said washing period and starting said fans for a drying period, and then stopping said fans.
 11. Apparatus as defined in claim 10 including a thermostatic switch in said exhaust duct and fire dampers in said exhaust and air supply ducts, and means in said system actuated by said thermostatic switch in case of fire in said exhaust duct to stop said fans, close said dampers, and operate said washing sprays for fire extinguishing purposes.
 12. Ventilating apparatus for kitchen cooking equipment comprising an exhaust duct for smoke and grease-laden air from said cooking equipment; an exhaust fan; a grease extractor and electrostatic precipitator in said duct; washing spray means for said grease extractor and precipitator; a control system; a start switch in said control system arranged to start said fan and energize said precipitator; a timing device in said system; and a stop switch arranged to stop said fan, deenergize said precipitator and start said timing device; said timing device then starting said washing spray means for a washing period, stopping said washing spray means after said washing period and starting said fan for a drying period, and then stopping said fan.
 13. Apparatus as defined in claim 12 including a thermostatic switch and fire damper in said duct, and means in said system actuated by said thermostatic switch in case of fire in the duct to stop said fan, close said damper and operate said washing sprays for fire extinguishing purposes.
 14. Ventilating apparatus for kitchen cOoking equipment comprising a hood adapted for mounting above said cooking equipment, an ascending exhaust duct having an inlet opening in said hood for smoke and grease-laden air from said cooking equipment, a grease and liquid collecting trough in the lower end of said duct and having a drain, a grease extractor in said duct above said inlet opening and trough, washing spray means in said grease extractor arranged to wash said grease extractor, an electrostatic precipitator in said duct above said grease extractor, washing spray means in said duct adjacent said precipitator arranged to wash said precipitator, and means including said duct for draining the washing liquid from said precipitator through said grease extractor into said trough to wash said grease extractor.
 15. Ventilating apparatus for kitchen cooking equipment comprising an exhaust duct for smoke and grease-laden air from said cooking equipment, a grease extractor in said duct, said duct extending upward from said grease extractor, an electrostatic precipitator in said duct above said grease extractor, washing spray means in said grease extractor, washing spray means for said precipitator, a control system having a timing device for programming said washing spray means in a wash cycle, said timing device initiating said wash cycle by starting said washing spray means for said precipitator, wash liquid from said precipitator draining through said duct and grease extractor for a first washing of said grease extractor, and said timing device thereafter stopping said washing spray means for said precipitator and starting said washing spray means in said grease extractor for a second washing of said grease extractor, and further including an exhaust fan in said duct, a start switch arranged to start said fan and energize said precipitator, a stop switch arranged to stop said fan, deenergize said precipitator and start said timing device, and means controlled by said timing device to stop said washing spray means in said grease extractor, start said fan for a drying period, and then stop said fan and timing device. 